The present invention relates generally to plasma antenna systems. More particularly, the present invention relates to plasma antennas having reconfigurable length, and optionally, reconfigurable beamwidth and bandwidth.
Traditionally, antennas have been defined as metallic devices for radiating or receiving radio waves, or as a conducting wire which is sized to emit radiation at one or more selected frequencies. As a result, the paradigm for antenna design has been focused on antenna geometry, physical dimensions, material selection, electrical coupling configurations, multi-array design, and/or electromagnetic waveform characteristics such as transmission wavelength, transmission efficiency, transmission waveform reflection, etc. Technology has advanced to provide many unique antenna designs for applications ranging from general broadcast of RF signals to weapon systems of a highly complex nature.
To maximize effective radiation of such energy, an antenna can be adjusted in length to correspond to a resonating multiplier of the wavelength of frequency to be transmitted. Accordingly, typical antenna configurations will be represented by quarter, half, and full wavelengths of the desired frequency. Efficient transfer of RF energy is achieved when the maximum amount of signal strength sent to the antenna is expended into the propagated wave, and not wasted in antenna reflection. This efficient transfer occurs when the antenna is an appreciable fraction of transmitted frequency wavelength. The antenna will then resonate with RF radiation at some multiple of the length of the antenna. Due to this, metal antennas are somewhat limited in breadth as to the frequency bands that they may radiate or receive.
Recently, there has been interest in the use of plasmas as the conductor for antenna elements, as opposed to the use of metals. This interest is due in part to the fact that plasma antennas can be designed to be more flexible in use than traditional metal antennas. Due to the dynamic reconfigurability of plasma antennas, some limitations previously known to exist with metal antennas are beginning to be removed.
It has been recognized that it would be advantageous to develop an antenna element having reconfigurable length. Such an antenna can provide many different antenna configurations resulting in increased antenna flexibility.
Specifically, the invention provides an antenna having a reconfigurable length, comprising an enclosed composition capable of forming a plasma that is operable as an antenna; an energy source; and an enclosure containing the composition. The energy source can be configured for applying variable energy levels to the composition to thereby form variable plasma configurations. Further, the enclosure containing the composition can be configured having a proximal end, wherein upon application of a first energy level to the composition, a first plasma length with respect to the proximal end is formed, and upon application of a second energy level to the composition, a second plasma length with respect to the proximal end is formed.
In accordance with a more detailed aspect of the present invention, the enclosure can include an orientation axis extending away from the proximal end, a first cross-sectional area with respect to the orientation axis, and a second cross-sectional area with respect to the orientation axis.
In an alternative embodiment, a method of reconfiguring a plasma antenna can comprise the steps of energizing a composition within an enclosure to form a plasma that is operable as an antenna, wherein the plasma has a first length extending from a proximal end; and altering the level of energy applied to the composition such that the plasma is reconfigured to a second length extending from the proximal end or toward a distal end. In one embodiment, the enclosure can be further defined by an orientation axis extending away from the proximal end, a first cross-sectional area with respect to the orientation axis, and a second cross-sectional area with respect to the orientation axis.